Gaining insight into the complexity of pain in patients with haemophilia: State-of-the-art review on pain processing.

Despite the high prevalence of recurrent, constant and/or widespread pain in patients with haemophilia (PwH), there is an immense lack of studies examining the (patho)physiology of pain in this population. This contrasts to the bulk of literature in other pain conditions, such as osteoarthritis, low back pain or rheumatoid arthritis. Understanding the complexity of pain allows to better assess and manage pain. In PwH, the first priority is always to exclude bleeding as a cause of pain. An important next step in pain assessment is the evaluation of the predominant pain mechanism (ie nociceptive, neuropathic pain or altered central pain processing) as the treatment approach will be very different according to the underlying pain mechanism. Pain assessment should include both physiological and psychological components. This review summarizes the evidence regarding nociceptive, neuropathic and altered central pain processing in PwH and serves as a research agenda to prioritize pain research in PwH.